1. Field of the Invention
This disclosure relates to shaped structures or containers and methods of manufacturing shaped structures suitable for use in packaging articles, for example pharmaceutical products. In particular, this disclosure relates generally to blister packages and methods of manufacturing blister packages.
2. Description of Related Art
Shaped articles, such as a shaped structure, shaped packaging, or shaped blister (e.g., blister packs), have been commonly used to package a variety of products, including pharmaceutical dosage forms, where each individual unit-dose of the product may be contained or housed separately from each other and protected from the environment. Pharmaceutical dosage forms (e.g., pharmaceutical compositions), especially those packaged as individual pre-measured doses, present significant packaging challenges, as many such products are susceptible to chemical or photo-degradation, chemical reaction and/or inactivation upon exposure to air, water, light or other environmental factors. Given the frequently considerable cost of such dosage forms, as well as the importance of delivering the intended dose of active ingredient(s) to a patient, losses or deterioration due to such environmental variables must be rigorously protected against.
Blister packs, also sometimes referred to as push through packs, have been used for many years to house individually separated products, including individual doses of pharmaceutical dosage forms. Typically, blister packs contain an array or series of blisters positioned in a square or rectangular-shaped film. Each blister contains the product therein and is covered with a cover layer such as a lidding secured to the film layer at least at the perimeter of the top of each blister. This lidding typically seals the blister and protects the contents therein by isolating the contents from the environment outside the blister. Any conventional lidding material and techniques well-known to those of skill in the art can be used to seal the formed recess. For example, polymeric sheet layers, metallic sheet layers such as foil, and bonding techniques associated therewith such as adhesives and the like can be used.
Blisters in blister packs may be manufactured by deforming a film layer, which may be accomplished by a number of different techniques known to those of skill in the art. Generally, shaped blisters are made by deep drawing, stretch-drawing or thermoforming of a film. Other blister-forming techniques include blow forming and vacuum forming softened films against a die. Blisters typically are produced in circular, square or rectangular overall cross-sections. Additionally, film layers may be in the form of a laminate including a metal foil coated with a plastic, for example to manufacture shaped articles where a section of the film is forced into a mold defining a recess having substantially similar dimensions to the desired shape of the blister to be created.
Blister packs can also have the additional function of acting as a mold during the manufacturing process of a product such as a pharmaceutical dosage form. In such an example, the blister pack acts as a mold for forming the product, as well as the containment and packaging for the in situ molded product. For example, in situ molded dosage forms can be prepared by depositing a liquid form of a composition directly in a blister and subsequently treating the blister and its contents such that the composition solidifies to form the final dosage form. This technique may be used to prepare freeze-dried or lyophilized dosage forms, for example. An example of such a technique is disclosed in Thompson et al., U.S. Pat. No. 5,457,895.
Processes for forming shaped packaging of laminates containing metal foils typically involve shaping tools including a stamp (i.e., a plunger), a die, and a retaining tool. As it is being deformed, the laminate is clamped securely between the die and the retaining tool, and the stamp is moved towards the laminate. As it is lowered, the stamp moves deeper into the openings in the die thereby deforming the laminate. In such a process, the flat laminate is converted into a shaped part exhibiting one or more recesses which are surrounded by an area corresponding to the original flat plane of the laminate. Only that part of the laminate in the region of the die opening can flow or be stretched to form a shaped part. The process methods known in the art are limited, however, because adequate lateral distance must be maintained between the stamp and the die opening in order that the laminate, especially laminates containing metal foil, can be deformed without cracks and pores forming, and the process should not generate folds in any layer of the laminate. In addition, heat treatments of such foils can generate irregularities in the formed film, and can make subsequent handling of the formed film difficult.
Two areas of concern with forming blister packs using methods known in the art are the uniformity of the material thickness after the draw is complete, and fracturing of the material. For example, current methods draw the film material in a manner that does not adequately distribute the stresses evenly in the blister, which results in uneven distribution of the material and leads to higher stresses and a greater likelihood of failures. In addition, the material is more likely to have thin spots that are prone to fractures. Thus, processes that can overcome these deficiencies are needed in the art.